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Book • ^1 



7 



UNIVERSITY OF WYOMING, 

Agricultural College Department. 



WYOMING EXPERIMENT STATION, 

LARAMIE, WYOMING. 



NOVEMBER, 1899. 



Some Experiments With Subsoiling. 

BY B. C. BUFFUM AND W. H. FAIRFIELD. 



Bulletins will be sent free upon request. Address : Director Experiment 
Station, Laramie, Wyo. 



Monograph 



s 



'^^ 

^ 



I 



Wyoiig AgrMM Mmt Slatloi. 



UNIVERSITY OF WYOMING. 



BOARD OF TRUSTEES. 

Hon. OTTO GKAMM, President, Laramie 1903 

GRACE RAYMOND HEBARD, B.S., Ph.D., Secretary, Cheyenne.1903 

HENRY L. STEVENS, B. S., M. D., Laramie 1903 

Hon. TIMOTHY F. BURKE, LL. B., Vice President, Cheyenne. .1901 

Hon. JOHN C. DAVIS, Treasurer, Rawlins 1901 

Hon. NATHAN S. BRISTOL, Casper 1901 

Hon. MELVILLE C. BROWN. Laramie 1905 

Hon. JOHN A. RINER, Cheyenne 1905 

Hon. S. CONANT PARKS, Ph. D., Lander 1905 

Hon. THOMAS T. TYNAN, State Supt. Public Instruction. .Ex-Offlcio 
President ELMER E. SMILEY, B. A., D. D Ex-Officio 

AGRICULTUR.VI- COMMITTEE OP THE BOARD OP TRUSTEES. 

H. L. STEVENS, Chairman Laramie 

OTTO GRAMM Laramie 

M. C. BROWN Laramie 

ELMER E. SMILEY Laramie 



PRESIDENT OF THE UMVERSITY OF WYOMING. 

ELMER E. SMILEY, B. A., D. D. 



STATION COUNCIL. 

E. E. SMILEY, B. A., D. D Director 

B. C. BIJF FUM, M. S., Vice Director, Agriculturist and Horticulturist 

A. NELSON, M. S., M. A Botanist 

E. E. SLOSSON, M. S Chemist 

W. C. KNIGHT, M. A Geologist 

C. B. RIDGAWAY, M. A Physicist and Meteorologist 

G. R. HEBARD, M. A., Ph. D Secretary 



W. H. FAIRFIELD, M. S Wyoming University Experiment Farm 

The Horticulturist in Charge, 

Wyoming University Experiment Grounds 



^; 



Some Experiments With Subsoiling. 

BY B. C. BUFFUM AND W. H. FAlRFlKf.D. 

The natural requisites for farming,- are soil, water, air, 
heat and sunshine. With one exception these natural bless- 
in<is are sufficiently abundant in the arid west. That ex- 
ception is water. The greatest question in our agriculture 
is how f'o make the most of our limited supply of this life- 
giving elenuMit. flaking use of our water supply would be 
a comiKuatively sim].'h^ matter if all the moisture which 
might b(- brought to the soil could be held there until plants 
could make use of it. I>ut water is never still. In seeking 
its common level, the sea, it runs otf the surface of the 
bind, or see}(s thiough the u]>j)er layers, escaping from be- 
low and that which is retained for a time by the soil is be- 
ing continually dissi])ated into the air as invisibh^ vapor. 
In our dry climate the e\ ai«)iation is so great that five or 
ten times as much water as comes to rhe eaitli in a year 
by rain would be lost by this process alone. Any jiractical 
jilan then of saving as much moisture as |)ossible for the 
use of cro]»s is of great im]>ortance and value. 

Tillage consists of stirring the soil and is as old as agri- 
culture. Its etf(^ct is somewhat complex. It breaks up the 
soil admitting aii". without which plants can not grow. It 
loosens the soil so it becomes suitable for planting the seed, 
as well as for tlu^ dev'elopment of ])lant i-oots and for 
the absorittion of watei'. brought to it by rain or ii-rigation. 
It disintegrat(^s the soil particles continually unlocking and 
n)aking available^ to the ]>lant new stores of ])lant food. It 
(h^stioys W(vds. Breaking u]> the surface foinis a blanket 
which ]ii'events the raj)id loss of water by eva]»oration. Is 
it enough that we shall cultivate the surface of the earth, or 



2 Wyoming Experiment Station. 

shall we find it profitable to extend tillage deeper into the 
hitherto undisturbed subsoil? 

Subsoiling is stirring- the earth below the region of the 
plow. For convenience we speak of the first eight inches 
of soil which may be turned over in plowing as the surface 
soil and all below this as the subsoil. Plowing turns the 
surface soil bottom side up. Subsoiling does not change 
the position of that part of the soil, but it breaks up and 
stirs the ground below the ordinary depth of plowing. This 
n)ay be effected bV a spur or prong attached to the plow 
which breaks up the soil at the bottom of the fufrow, or it 
may be done with a separate implement to be drawn along 
through the soil beneath the bottom of the furrow after 
the i»low, to stir the ground to greater depths than can be 
done with a small attachment to the ordinary plow. This 
implement is called the subsoil plow and usually consists 
of a mole or a more or less flat piece of iron pointed at one 
end and attached to the beam by a strong flat vertical blade. 
When drawn through the soil in the bottom of the furrow 
left by the plow this implement can be made to break up 
and stir the subsoil to a depth of fiom one to two or more 
feet. 

The advantages claimed for subsoiling are that it makes 
more room for root development, and enables the plant to 
extract food and moisture from a greater area, and that by 
loosening up more of the soil its capacity for absorbing and 
retaining moisture is increased. By the absorption of 
greater amounts of moisture in winter and spring it is sup- 
posed that subsoiling ]>rovides against summer drouth. It 
is reasonable to suppose that this is what would happen 
and the many favorable reports on subsoiling from humid 
and semi-arid regions indicate that loosening the lower lay 
ers of soil is a valuable way of conserving moisture for those 
regions. Before discussing the efl"ects of subsoiling in Wy- 
oming the dift'erences between a truly arid region and one 



l>^onie E.rpcr'nnents With Stibsoiling. 



which is only semi-arid should be briefly pointed out. Places 
where the annual rainfall is less than fifteen inches are gen- 
erally called arid. The air is dry; the evaporation is grt^at; 
the rainfall is not suttlcient to niatui'e cultivated crops. In 
the semi-arid region the rainfall is mort' than fifteen inches 
and may be enough to mature i)rofitable crops if the moist- 
ure can be stored u]) in the soil and saved until the crop can 
make use of it. In ^^'yoming the conditions are truly arid 
unless it be in the extreme northeastern portion of the state. 
There is little precipitation during the fall and winter, so 
very little moisture escapes by running directly off the sur- 
face of the land. If, then, subsoiling is not necessary to in- 
crease the holding ca] acity of the soil, and absorb water 
during time of extra sui)i>ly. will it save more of the water 
which may be a]»i>lied artificially during the growing season 
and will this and other advantages make it ])rofitable to go 
to the extra ex]>ense of such tillage in our state? 

To solve this question we have been experimenting with 
subsoiling for three years and this bulletin is ])uhlished 
to report the results obtained. The experimi'ut was con- 
ducted in the same manner on the several ex]»eriment farms 
in the state. Unfortunately the records of the Land(M- farm 
were lost in transit, and the publication of this bulletin has 
been long delayed with the hope they might be found. The 
soil of the Lander and Sundance farms is almost identical, 
the altitude of the two places is not far different and while 
the experiment in subsoiling was only carried out one sea- 
son at Sundance, a comparison of the results obtained would 
be highly interesting. The climate of Sundance is serai- 
arid or sub-humid, crops being raised without irrigation, 
while that of Lander is arid and no crops are raised without 
irrigation. A comparison of the results at these places 
would give more trustworthy evidence of the difference in 
value of subsoiling under such conditions of climate and 
farm practice. 

The experiment was begun in the spring of 189G and ear- 



Wyoming Experiment Station. 



I'ied out that year at Laramie, Lander, Sheridan, Sundance 
and ^Vheatland. In 1897 the cropping was repeated on 
tlie same land at Laramie, Lander and Sheridan, and in 
1S!>S, at Laramie only. 

PLAN OF THE EXPERIMENT. 

Following i.s an <»utline of tlu^ instructions for subsoiling 
which, with slight modifications for each locality, were fur- 
nished the farm suiierintendents in the spring of 1896 — 

This ex])eriment is to be carried on alike on each of the 
farms. Select a suitable acre plat. Plow the land over the 
whole }>lat the same and let all other o]>erations such as 
harrowing, etc., be the same for all parts of the plat. Sub- 
soil thoroughly one-half of the plat. Mark carefully and 
pernmnently the line where the subsoiling sto})s. 

Divide the i)lat into four equal parts so one-half of each 
fourth is (»n the subsoiled iiortion and one-half on the part 
merely i)lowed. 

Ljion the first fourth acre i)lant oats. 

Lpon the second fourth acre plant potatoes. 

L})on the third fourth acre jdant wheat. 

Divide the last fourth into two jiarts and plant beets on 
tlit^ one and coi-n on the other. 

Treat the crops on the plowed and subsoiled land the 
same throughout the season. Kee]» careful notes of any 
variations on the two parts of each plat. 

When you harvest each cro]t cut out a strip six feet wide 
along the line on which the subsoiling stops, casting out 
the cro]> from a strip three feet wide on each side of this 
line, which part is to be taken no account of in figuring up 
the yields on subsoiled land or land not subsoiled. This is 
iujportant as the effects on the ground treated or untreated 
will reach across the line some distance. 

Measure the area in square feet occupied by each crop to 
be used in figuring ui» the yields. In the case of rowed 



*S'o?Me E.Tperiments With ^nbsoiling. 



crops, allow for the number of rows at their distance apart 
and take the length of row on treated and untreated land. 

This experiment will be repeated upon the same ground 
for a number of years to determine the effect of subsoiling 
on soil and crops — . 

In 180S some additional land was subsoiled and on one 
plat of oats covering one-half acre an accurate measurement 
was made of the irrigation water used. In 1897, the next 
year after the land was subsoiled for this experiment, the 
Physicist made a study of the moisture content of different 
soils which was published in Bulletin No. 35 of this Station, 
a resume of which is used in this report. 




Results of the Experiments. 

Plants of different kinds act very differently when grown 
on subsoiled land. The effect on a crop of loosening the 
soil to a depth greater than by ordinary plowing is also 
very different on diffei'ent soils and under varying climatic 
conditions. Our experiments were carried out in widely sep- 
arated parts of Wyoming and with the more important crops 
raised in each section. Again there are often accidental 
variations which throw doubt on the value of an experi- 
ment and where possible the work has been repeated more 



6 Wyoming Experiment Station. , 

than one season. The conclusions reached have been care- 
fully drawn and we believe the results of these experiments 
are worthy of consideration by our farmers. 

The soil on the station farm at Laramie contains con- 
siderable gypsum and lime carbonate, is quite sticky when 
wet and becomes firmly compacted below the plow. The 
land selected for this experiment had been cultivated for a 
number of years. It was plowed about eight inches deep 
and one-half the plat was subsoiled to a depth of fourteen 
to sixteen inches in April, 189fi. The ground was so hard 
that four horses were required to pull the subsoil plow 
and if larger areas were to be treated six horses would be 
necessary. The land was not again subsoiled but the dif- 
ference in the yield of crops produced was observed for 
three seasons. This shows the lasting effects of subsoiling 
and the return which may be expected from one such treat- 
ment, and throws light on the absorption and retension of 
water through the entire year. The second year there was 
a slight difference in the depth of the plowing on the two 
portions of the plat. Where the land had been subsoiled 
the plow sunk one to three inches deeper than on the plowed 
portion. 

On the other station farms in the state the plowing and 
subsoiling was done in the same manner as at Laramie, 
At Sheridan the soil is clay underlaid with true hardpan. 
It is not known to what extent this hardpan was broken up 
by the subsoil plow. At Wheatland the soil conditions are 
much the same as those at Laramie. At Sundance the soil 
is deep, contains gypsum and much of the subsoil consists 
of red shale which is not tenaceous but comparatively easy 
to work. 

The average rainfall is nearly ten inches at Laramie;, 
about the same at Wheatland, nearly fourteen inches at 
Sheridan and twenty inches at Sundance. At Laramie and 
Wheatland from fifty to sixty percent of the total annual 
precipitation falls in the growing months of May, June,. 



Some Experiments With Suhsoiling. 



Julv and Aiiffiist. The greater amount of precipitation at 
Sundance and the fact that the land was not irrigated un- 
doubtedly accounts for some of the difference noted in the 
effects of subsoiling between the Sundance and other farms. 

Subsoiling for Grain Crops. 

Table I. gives the effects of subsoiling on the yields of 
wheat. Though the difference was not great, the yield from 
the subsoiled land was less than that from the land only 
plowed, at Laramie, the year the subsoiling was done. The 
second and third years there was a slight increase in yield 
from the subsoiled land. The increase in the yield of straw 
is greater in proportion than that of grain. This condi- 
tion would be expected as the increased feeding area of the 
roots and other conditions favoring rank growth would 
produce more straw and less grain where the growing sea- 
son is short. The reason for this is indicated in Wyoming 
Station Bulletin No. 37 on the "Stooling of Grains." It 
is a general law that under adverse conditions plants strive 
to mature seed in order to reproduce themselves. Under 
these conditions then, grain will mature earlier and pro- 
duce more seed in projwrtion to the rest of the plant than 
where everything is favorable to long continued growth. 
Table I. — Subsoiling for li/ieat. 

Yields in Pounds per Acre. 





Laramie. 


Sheri- 
dan. 


Wheat- 
land. 


Sl'NDANCB. 




Straw 

and 
Grain 


Grain 


Grain. 


Grain. 


Straw 

and 

Grain. 


Grain. 


/Subsoiled 

Fi-Y—^!°r-:: :::::::: 

' Loss 


2(127 


!»43 

997 


3000 
2550 


l(iI4 


3920 
3441 


1440 
1160 


r>4 


450 


112 


480 


280 


Second i Subsoiled 


2174 
1S94 


901 

S76 


2700 
1950 








280 


25 


750 












( Gain 


2170 
2127 


908 
833 










43 


85 






1 



Wyoming Experiment Station. 



The increase in yield of wheat at Laramie the second and 
third years on the hind which had been subsoiled is but 
little more than enough to balance the decrease the first 
season. At Sheridan there was an increase in yield the 
first year of seven and one-half bushels and the second year 
of twelve and one-half bushels on subsoiled land. At 
Wheatland and Sundance the increase on subsoiled land 
was small but was over twice as much at Sundance as at 
Wheatland. 

The results with oats are given in Table II. The length- 
ening of the season for oats by subsoiling was more marked 
than with wheat. At Sundance the oats on the subsoiled 
portion of the plat seemed to be making better growth dur- 
ing the first ])art of the season but, when harvested. Super- 
intendent Hoyt reported a smaller yield than was obtained 
from the land treated in the ordinary way. At Laramie 
the oats were later in reaching maturity on the subsoiled 
land. It may be stated that late varieties of nearly all crops, 
if not interfered with by frost, produce heavier yields than 
th(»se which require only a short season in which to ma- 
tui-e. Lengthening the growing season for the same variety 
would be expected to increase the yield, but at the high 
altitude of the land over a large part of Wyoming the time 
between late and early frosts is comparatively short and 
earliness in ripening is a most important factor. There 
was a slight increase in yield of oats the first two years, but 
the third season the decrease in crop was almost enough 
to balance the gains of the first two seasons, though whether 
or not the efi^'ect the third season was due to subsoiling may 
be questioned. 

At Sheridan there was a loss of seventy pounds more of 
oats the first year than was gained the second year by sub- 
soiling. At ^Mieatland there w^as a small increase on the 
subsoiled land, but the variation was small, probably not 
more than would be obtained on any two plats, though 
treated exactly alike. To all appearances the yields of oats 



^onw Experiments With Huhsoiling. 



9 



were not luaterially influenced at any place by subsoiling 
the land. 

Tablp: II. — Subsoiling for Oats. 

Yield in Pounds per Acre. 







Laramie. 


Sheri- 
dan. 


Wheat- 
land. 


Sundance. 




Straw. 


Grain. 


Grain. 


Grain. 


Straw. 


Grain. 




1 Subsoiled 

) Plowed 


4;J90 
3S98 


1520 
1345 


•5070 
3360 


1898 
1014 


1960 
2224 


512 

648 


First Year 




492 


175 


290 


184 


356 


— 




V Loss 


136 


Second 


(Subsoiled 


'WyS 

;«7s 


1345 
1194 


2700 
24S0 








Year. 


( Gain 


177 


151 


220 








Third 


/ Subsoiled. ... .... 

) Plowed . . . 


8(i4r> 
4445 


1302 
1526 












800 


224 












'Loss. 





Because of the high altitude with the accompanying short 
seasons and cold nights, corn is not grown at Laramie, so 
barley was planted on one i»ortion of the subsoiled plat 
at this place and corn was grown at Sheridan, Wheatland 
and Sundance instead of barh^v. The results with barley 
and corn are given in Table III. It is doubtful if any ef- 
fect on the yields of barley one way or another can be tracpd 
to the subsoiling. The first year there was less straw and 
more grain on the subsoiled land. The second year this 
was reversed, there being more straw and less grain where 
subsoiled, and the third year there was aproximately no 
diflereuce in the i)roductiou of straw, but there was quite 
a decrease in the yield of grain. 

Subsoiling for corn did not pay at the siib-stations ex- 
cei>t at Sundance where a good increase in yield was ob- 
tained. At Sheridan there was quite a large decrease in 
yield of corn the first season, and no difference the second 
year. Sui>erintendent Lewis reported that the corn did 
not mature as well on the subsoiled land. The first year 
the estimated yield on the subsoiled part of the plat was 



10 



Wyoming Experiment Station. 



thirty bushels per acre, and on the land not subsoiled thirty- 
five bushels i>er acre. Ten per cent, of the corn on the land 
merely plowed ri]>ened thoroughly, while all the grain from 
the subsoiled portion of the plat was soft and immature. 
The second season fifty bushels of mature and thirty bushels 
of soft grain per acre were harvested from each portion of 
the plat. To com])are with others in the table, these yields 
have been reduced to pounds by using the weight of seventy 
pounds per bushel for corn in the ear. 

At Wheatland during the season of 1896, the supply of 
water for irrigation was somewhat limited, and if the crops 
suft'ered for water, as they probably did to some extent, 
those on the subsoiled land would be expected to have the 
advantage. Mr. ]M. R. Johnson, the superintendent, states 
that all the crops made a better growth on the subsoiled 
land, that they seemed to withstand drouth better, and that 
the quality as well as the quantity of the product, indicated 
beneficial effects from subsoiling. The corn gave an in- 
creased yield of 80^ pounds ]»<'r aci'e on the subsoiled land. 

Table III. — Subsoiling for Bat-ley and Corn. 

Yield in Pounds per Acre. 





Lar.\mie. 


Shkri- 

UAN. 


Wheat- 
land. 


Sun- 
dance. 




Barley. 


Corn. 


Corn. 


Corn. 




Straw. 1 Grain. 


Grain. 


Grai^. 


Grain. 


/ Subsoiled 

„. ,, ) Plowed 

First Year, ^'^i^ 


2044 1 1325 
2989 1 r292 


2100 
24r)0 


3590 
2227 


3008 
2416 


— 33 
45 - 


350 


363 


592 










/Subsoiled 

Second J Plowed 


4(102 
4123 


1479 
1668 


:i500 
3500 


1 


479 











' Loss 


— ! 189 




^Subsoiled 

Third j Plowed 


2169 
2175 


527 
752 










6 


225 








I Loss 





Soine Experiments With Suhsoiling. 



11 



Subsoiling for Root Crops. 

The fact that deep soils are favorable for the growth of 
roots is recognized everywhere, and as would be expected 
subsoiling produced more marked effects on the yields of 
root crops than it did on grains. In Table IV., reporting 
the results with root crops, it will be seen that in every 
trial there was increased yield from the subsoiled land, and 
in some instances there are important gains. The lasting 
effect of subsoiling is well brought out in this table. All 
the tables show that, at SlKM'man, where the experiment 
was cari'icd out two years, and at Laramie where results 
w'ere obtained three seasons, the beneficial effect of subsoil- 
ing is greater the second year than it is the season the sub- 
soiling is done. This indicates that it would be advisable 
to subsoil in the fall rather than in the spring. The third 
year the soil has probably become compacted again so the 
effect is much less than it is the first two seasons. 

Table IV. — Su^soi/m^ for Root Crops. 

Yield in Pounds per Acre. 





L.^RAMIE. 


Sheridan. 


Wheat- 
land. 


Sundance. 




o 

2 

o 

a. 


cs 


.9- 
'c 


o 

O 
0. 




o 
o 

a. 


CO 


o 

2 
o 

PL, 


m 


1 Subsoiled 

First Year.. Plowed 






8695 

8380 

315 


i28.-iS| lasoo 

10620 t2(iOO 


2425 
2151 

274 


8302 
8009 
293 


S224 : 17161 
6960 1 14S41 


( Gain 






223.S 


1260 


1264 


2320 


c^^„„^ \ Subsoiled 

-" lSr^.-::::: 


3672 
2620 


12893 
IIMS 






28700 
24795 










1052 


1250 






3905 










( (jam 


()940 
6865 


5450 
4522 
















75 1 928 

















POTATOES— At Laramie the jiotatoes planted the first 
year failed to grow because the soil was too dry. The second 
and third years the stand was poor and small yields were 
obtained, but there was a good increase of crop on the sub- 



12 



Wyoming Experiment station. 



soiled land. In Table IV. only the yields of potatoes which 
were of sufficient size for market are reported. The pro- 
portion of large and small tubers on the two kinds of ground 
and the increase in size on the subsoiled land is of interest. 
Table V. gives the yields of large and small potatoes, the 
percent marketable and the weight of the largest twelve 
tubers from each portion of the plat at Laramie in 1897 
and 1898. The difference in yield in 1898 is small and 
there was practically no difference in the size of the pota- 
toes, indicating that little effect on this crop was produced 
by the lower soil having been loosened up three years be- 
fore. The second season after subsoiling, however, there 
was not only a large increase in the yield, but in the size 
of the tubers as well. 



'I'ablk V. — ■ Effect of Suds<7i/ino- on Size of Potatoes. 

at Laramie, Wyo. 





1897. 


1898. 




Yield. 


Percent 
Market- 
able 


Weight 

of 
largest 
twelve. 

5.1 
4.5 


Yield 


Percent. ^'^V^^' 




Large. 


Small. 


Large. 


Small. 


able. 


largest 
twelve. 


Subsoiled 

Plowed 


:{(i72 
2(520 


1552 

ItiCO 


70. :i 

(il.2 
9.1 


"1)040" 
(i8()5 
75 


2417 
2212 

205 


74.2 
75 . 5 


4.() 
4.6 


Gain 


1052 


802 


0.(i 





At Wheatland the subsoiling ]»roduced little effect on 
])otatoes. The incrcnise in yield of marketable jxitiitoes was 
only 274 pounds. Of the entire cro]) (12.8 ps^rcc^nt were 
marketable on subsoiled Innd, and on the land not sub- 
soiled the marketable tubei's were 08.fi ]>er cent of the whole 
crop. At Sliei-idan and Sundance the small potatoes were 
not re]K)rted, but at Sheridan tlu' largest 12 tubers from 
suhsoih^l land weighed six and om^-half pounds and from 
])lowed land six ])ounds. 

SUGAR REETS — Subsoiling gave satisfactoi'v increase 
in yic^lds of sugar beets at every jilace except Sheridan. At 



Some E.iperiineiits With Hubsoiling. 13 



Laramie the increase iu size of the beets is worthy of special 
mention. Not only were the hirgest twelve very different, 
from the two plats, but the average size of the roots was 
much larger on the deep soil. In 1897 the largest twelve 
roots from the subsoiled plat weighed nineteen pounds and 
from the }>lat not subsoiled twelve roots weighed eleven 
pounds. In 1898 the dift'erence was less. 

Twelve of the largest beets from the subsoiled plat 
weighed in the aggregate seven and one-half pounds and 
from the plowed land six and one-half pounds. Analysis 
of the beets showed slightly better results from the land 
not subsoiled. Beets from subsoiled land contained 19.7 
percent sugar and had a jturity of 88.2. while those from 
the adjoining ]tlo\\('<l land (•ontain(Ml '2().l\ percent sugar 
and had a jmrity of 92.7.* The analyses were made fiom 
the cro]> of 1897. tlie second year aftcM' subsoiling. 

SUBSOILING, IRRIGATION AND SOIL MOISTURE. 

Tln^ subsoil jdats were suuill, and as it was necessary to 
treat the croi»s alike on borli parts of tlie ])lat, it was im- 
})ossible to measure the amount of water used on each ])or- 
tion. An experiuKmt was carried out with different 
amounts of watei- on the j)otatoes growing on the subsoiled 
land in 1897. Measurements wtM'e made of the total amount 
of water used on the i.lat. one half of which was subsoiled 
and also on anotluM- subsoiled ])lat, and we ar<^ able to com- 
pare these measurements with the amount of water us(^d 
on other fields. During the season of 1897 the Physicist 
made a series of moisture determinations on the diff'erent 
soils and ])ublished the results in Bulletin No. :i5, a resume 
of wliicli is shown in the accompan.\'ing diagram. These 
observations i^nable us to diaw some conclusions in relation 
to the soil moistui'e and the usi^ of ii-rigation water on such 
dee])ly tilled soils at Laramie. 

In 1890 the barlev, oats and wheat, were iriigated twic<\ 



*See Wyoming Station Bulletin No :%. Page J!(" 



14 Wyoming Experiment Station. 

on the acre of laud one-half of which was subsoiled. At 
the first irrigation on July 2, enough water was applied to 
cover the land 11.4 inches deep and at the second irrigation 
enough water was applied to cover the land 6.12 inches 
deep, or a total depth for these crops of 17.52 inches. The 
precipitation for the year was 10.75 inches of which 4.75 
inches fell during the months of May, June, July and August. 
This gave a total of 22.27 inches for the growing season or 
28.22 inches of water for the year. The same year wheat 
and oats on other fields received enough water by irriga- 
tion to cover the land to a depth of 14.88 inches, and barley 
received 14.52 inches of water, showing that enough more 
water was applied to the acre, one-half of which was sub- 
soiled, to cover the whole plat three inches deep. If this. 
was due to the effect of subsoiling it means a requirement 
of six inches more water on the subsoiled land. Unfor- 
tunately the record of measurements of water on the sub- 
soiled plat was broken, so it cannot be reported for 1897, but 
in 1898, trustworthy measurements were secured. The wheat, 
oats and barley were irrigated twice. On June 24, enoug^h 
water was applied to cover the land 11.52 inches deep, and 
July 18 enough water to cover it 9.12 inches deep or a total 
of 20.64 inches. Including the rainfall, the land received 
enough water during the growing season to cover it to a 
depth of 25.22 inches, and in the year 28.26 inches. It is 
not possible to draw conclusions in regard to the effect of 
the subsoiling on this plat in 1898, as other crops of the 
same kind received varying quantities of water, some more 
and some less than this amount. 

On another plat, however, which was subsoiled in the 
spring of 1898 and planted to oats, the amount of water 
used in ii*rigation was very large. The land was irrigated 
twice. At the first irrigation on June 27, enough water 
was used to cover the land 30.84 inches deep, and all of it 
was absorbed by the soil. At the second irrigation, July 
11, enough was used to cover the land 13.44 inches deep, 




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Some Experiments With Subsoiling. 15 

making a total for the season of 44.48 inches, or 3.69 feet. 
Includiug the rainfall, this gave a depth of water brought 
to this laud in the year of 51.91 inches or for the growing 
season of 48.47 inches. The amounts of water used on other 
[>lats of grain in 1898, was 1.90 feet on one held of oats, 2.58 
feet for oats on sod, 1.55 feet for oats and cultivated grain, 
2.70 feet for one plat of barley, 1.74 feet for one plat of 
wheat and oats, and 3. 03 feet for one field of wheat, which 
was irrigated three times and given an unusual amount of 
water. 

The illustration of five feet of soil on the Experiment Sta- 
tion is made from a photograph taken one year after the 
subsoiling was done. The upper eight inches of dark soil 
is the portion turned over each year by the plow. The next 
six or eight inches of subsoil shows the effect of having 
been loosened by the subsoil plow, leaving it porus. On 
the native plains the soil below the first one or two feet 
may not have been wet for ages, as the natural rainfall is 
not suflflcient to wet more than the first few inches of sur- 
face, and there is practically no difference in composition 
between the surface and subsoil. Breaking up the layer 
which is compacted by the plow in the bottom of the furrow 
gives the water a new reservoir below the plowed land and 
affords a means of escape by seepage, which would account 
for the large amounts necessary to soak it up when irrigated 
and perhaps also for easy dissemmination and loss of the 
moisture afterwards. 

In 1898 the potatoes on the plat, one-half of which was 
subsoiled, were divided into two parts. One part was ir- 
rigated twice, using only a small amount of water each 
time and the other part was irrigated three times. Those 
irrigated twice received enough water to cover the land 
2.04 inches deep on July 28, and 1.56 inches deep on August 
4. The ones irrigated three times received the first irriga- 
tion on July 7, when enough was applied to cover the land 
10.20 inches deep. At the other two irrigations they were 

-(2) 



16 



Wyoming Experiment Station. 



given the same amounts as the potatoes which were irri- 
gated but twice. The results are given in Table VI., which 
shows the amount of water applied and the yields on land 
subsoiled and not subsoiled. 

Table VI. — Potatoes with Two and Three Irrigations on Subsoiled Land. 

Laramie, Wyo.,1898. 





Total 

amount of 

water 

applied. 

Inches. 


Yield on 

land 
plowed 
Pounds. 


Yield on 
subsoiled 

land. 
Pounds. 


Average 

yield. 
Pounds. 


\Veight of 
largest 
twelve 

plowed. 

Pounds. 


Weight of 
largest 
twelve 

Subsoiled. 
Pounds. 


Irrigated twice 

Irrigated three times 


3.C 

i;i.8 


4972 
8759 


5290 
8.591 


5131 

8675 


3.6 
5.6 


3.9 
5.3 




10 2 


3787 


3301 


:i544 


2.0 


1.4 











This shows an increase due to the increased amount of 
water applied, of over seventy-six percent on plowed land, 
and sixty-two percent on subsoiled land, the average in- 
crease being about sixty-nine per cent. The fact that in- 
creased water applied in irrigation did not increase the 
crop as much on subsoiled land as on the land which was 
plowed is in favor of the subsoiled land as it indicates that 
the crop actually needed less water to produce the same 
yield. This may be true, as the variation is small and may be 
accidental, and it is possible and i^robable that more water 
was actualh' absorbed by the subsoiled portion when irri- 
gated. It is unfortunate that we are not able to make a 
like comparison the first and second seasons after subsoil- 
ing. 

If moisture comes to the soil during any part of the year, 
the friends of subsoiling claim that it is retained and made 
more available to the crop. The study of the moisture in 
the soil of the ditferent ])lats at Laramie in 1897, which was 
made by the Department of Physics, does not seem to bear 
out such statement. The accompanying chart illustrates 
the difference in moisture content of the soils on sod land, 
on land which was plowed in the usual way and on the sub- 
soiled land. The determinations of moisture were made 



iconic l'J.ri)critiiviits WitJi Siihsoilhifj. 17 



daily and these have been averajjed for each month. The 
saniph'S were taken to tlie depth of one foot by driving 
tubes about one inch in diann^er into tlie soil. On the 
loose ground some of the soil might be diiven down in front 
of the tube instead of entering it, but the sam]>les were 
carefully taken and no elTcct of the kind was noted. The 
vertical black lines in the chait iipreseut the average jter- 
cent of moisture in tlie soil which is also (expressed in iig- 
urcs at the to]» of each column. The last three columns at 
the right re]trcseut the average j/ercent of moisture for the 
summer. The lowest moisture content observed was 2.52 per- 
cent in sod land, Sei>teniber 24. The highest percent observed 
was 22.25 on the land j)lowed but not subsoiled and 
imnxdiatcly after irrigating it. The amount dro])])ed to 
19.7 percent the second day, and to 15.7(5 ]>ercent the 
third day. (^n the subsoiled jiart of I he jilat after irrigat- 
ing the percent was 21.15 the first day, 21.7(1 the second day, 
decreasing to 1(5.28 the third day aftei- apjtlying the water. 
There is little ditfei*ence in the average moisture of the sur- 
face soil on th(^ ].'lowed land and that subsoihd, but what 
dilference there is shows less moisture on the subsoiled 
land throughout the summer. Thes(> facts indicate that 
more water was needed at Laramie to in-igate sul)soiled 
land and less of it was retained by the surface soil for the 
use of the i)lants growing thereon. It is possible there was 
more water in the soil below the deptli of these sam])les on 
the sul)soiled jtlat, but the ditferenct- was not great enough 
to produce markf^l effects on the crops. At Shei'idan the 
Ku]Huintendent states that mVu'e water was re(iuired at the 
first ii-rigation and less at the second on the subsoiled land. 
At Wheatland the crojis se<Mned to b(^ less aifected by drouth 
wlieic subsoiled. This n)ay have been du(^ to an excess of 
water absorl>ed by the subsoiled land wln^n it was irrigated. 





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^ome E.Tperiments With ^uhsoiling. 19 

DOES SUBSOILING PAY ? 

The test of the advisability of any operation on the farm 
lies in the final result measured in dollars and cents. Sub- 
soiling,- is an expensive operation which more than doubles 
the ordinary cost of ivreparinfj^ the land for the crop by plow- 
ing. The cost of snbsoilinfj- will vary with the condition 
of the soil and the price of labor. The cheapest it could 
hi' done on lar^e areas, and thoron<»hly done as in these 
experiments, would be at a cost of not less than three dol- 
lars ])er acre, ^^'here w<^ broke up the subsoil to a depth 
of fourteen to sixteen inches, on small plats the expense 
was five or six dollai's per acre. Unless it increases the 
yield, improves the quality and therefore the value of the 
croj), or reduces the expense of pi-oducin^ it, or requires 
less water so the same sup]>ly will irrif^ate more land, the 
practice of subsoilin*;- cannot be i-econimended as one to be 
adopted on the farm. 

jReferrinji- to Tal)l(^ I. in which tlic yields of wheat on sub- 
soiled land and on land prcjfai'cd in the ordinary way are 
com]>ared. it is evident that the ai-cumulated increase for 
three seasons at Laramie would not ])ay the exj)ense of 
one subsoiling. At Shei'idan the increast- of 450 pounds 
of wheat jter acre the fii'st y(^ar and T-IO pounds the second 
due to subsoiling would give a total value of twelve dollars 
jier acre more from the snbsoiled land. If the subsoiling 
cost four dollars per acre more than the ordinary expense 
of plowing-, the margin of j)rofit is larg-e (Miough. Even 
though we allow for a considerable increase in yields the 
second year at Wheatland and Sundance, snbsoiling would 
not ]>ay foi- wheat in these localities. 

The results with oats as given in Table II. do not show 
any marked or unifoi-m improvement in the crop. So far 
as our experiments may be relied upon as showing the true 
effects of subsoiling in this state, the indications are that 
it will not pay to so prepare the soil for oats. The same 



20 Wi/uiniii(j Experiment Station. 

statement may be made for barley and corn nnless it be at 
Sundance, where the increase the first year and the proba- 
bility that there would nlso be a like increase in the crop 
the second year, indicate that subsoiling for corn might pay 
in that region. 

Subsoiling for root crojts did not give a return the first 
year at Wheatland, large enough to pay the cost, though 
the (piality of the crop was im])roved and the increase the 
second season might leave a i)rofit. At I.aramie the in- 
crease in the potato cro]) the second year (see Table IV. 
page 11), would be worth .fl0.50 to |i;i.O() at the local mar 
ket i)rice. On the Sheridan farm the increased yield of 
potatoes the first year was worth from |11 to $20, and at 
Sundance from |0 to fl2, depending on the market price. 
The value of sugar beets for stock food would make the in- 
creased yields from subsoiled land at Laramie, Sheridan 
and Sundance profitable. As a rule we beliine that sub- 
soiling for root crops will bring a ]»rofitable return. 

Whether or not subsoiling will ])ay de] tends largely on 
local conditions and the kind of crop. Beforv ado])ting so 
expensive a system of tillage the farmer should satisfy him- 
self in regard to whethei- it will bring a profit on his land 
by making small trials. Our results can not be said to in- 
dicate that subsoiling in regions which depend on irrigation 
will materially assist in saving the moisture or make ir- 
rigation less necessary. It is tiue that subsoiling ap- 
jjarently mitigated the effects of drought scunewhat in 
Wheatland, though the increase in the value of the cro]» 
was not sufficient to ])ay for the ex]>ense incurred. It is 
])ossible that, where w'ater for irrigation is scarce, and other 
conditions are favorable, subsoiling might make the water 
which is available go farther in maturing a croj), though we 
have been unable to prove any valuable saving of moisture 
where the subsoil is nmde porus. 



8o?n€ Experiments With Suhsoiling. 21 



SUMMARY. 

The expense of Hubsoiliii"; to depths of sixteen or 
eighteen inches is from three to six dollars per acre. 

Subsoiling is probably more valuable in semi-nrid or 
humid regions than where irrigation is practiced. 

The effects of once subsoiling the land may continue for 
three or more years and under our conditions are more ap- 
parent the second season after the subsoiling is done than 
they are the first. 

If subsoiling is to be practiced, we recommend doing it 
in the fall. 

Subsoiling does not produce a uniform effect on the 
grains. Under certain conditions it may pay for wh(^at 
raised by irrigation. We have not found it profitable for 
oats, barley, or corn. 

Grain takes longer to mature on subsoiled land. At high 
altitudes where the season is comparatively short it is 
doubtful if subsoiling for grain is advisable. 

The quantity and quality of root crops are greatly im- 
proved by subsoiling the land. Subsoiling can be generally 
recommended in this state for potatoes. 

Under our conditions subsoiling has increased the amount 
of water needed to irrigate the land and apparently is of 
little value in conserving moisture. However, if no water 
could be applied by irrigation during the summer, the fill- 
ing with moisture in the winter or spring by rainfall or ir- 
rigation of the reservoir formed by subsoiling, would be 
beneficial. 



